I’m not sure if a finer resolution is possible, but let me turn the question around - is it necessary? The size of antennas you would be able to put on there are going to have a wide enough beamwidth to be off by a number of degrees and still be fine…
Yes, I know that 1 ° is more than enough for a yagi, but I would want just to know if the rotor could work as a telescope frame : the engine of follow-up works permanently and not by surge.